The disclosed embodiments relate to updating and maintaining electronic files.
Software running on a processor or central processing unit (CPU) to provide functionality in the host device often changes over time. The changes may result from the need to correct bugs, or errors, in the software files, adapt to evolving technologies, or add new features and functions. In particular, embedded software components hosted on mobile wireless devices often include numerous software bugs that require correction.
Software includes one or more files in the form of human-readable American Standard Code for Information Interchange (ASCII) plain text files or binary code. Software files can be divided into smaller units that are often referred to as modules or components. A UNIX platform or personal computer (PC) includes multiple software components, and each of the software components is managed and updated independently through a file system supported by a corresponding operating system (OS). Information used to update software files or software components hosted on UNIX platforms or PCs can be transferred through the Internet or loaded from a secondary storage medium such as a floppy disk, a compact disk read-only memory (CD-ROM), or a compact flash card.
In contrast, in mobile wireless devices, a real-time operating system (RTOS) is typically used in which all software components are linked as a single large file. Further, no file system support is typically provided in these mobile wireless devices. In addition, the single large file needs to be loaded, or embedded, into the device and updated using a wireless communication link or over-the-air (OTA) link like a radio link. Consequently, problems arise with regard to delivering software file updates to mobile devices like cellular telephones and other mobile communication devices, personal digital assistants (PDAs), and personal computers.
One solution to the problem of delivering large files to mobile devices for use in updating files of the mobile devices uses difference programs to generate difference files. The difference files include data that describes how a revised or new file differs from an original file. While use of the various difference programs helps reduce the size of the transferred files, issues remain as to the reliability associated with provision of the updates to the mobile devices.
For example, file delivery and updating via an OTA link carries with it an increased probability of failure. These failures generally relate to failures associated with components of the service provider network and/or components of the numerous mobile devices that must receive the updates. Examples of the types of failures that can occur include mobile device hardware failures, software failures, failures relating to power (battery) exhaustion, and failures as a result of disconnections of the mobile device from the network during the update process. Regardless of the cause of the update failure device manufacturers and service providers must ensure, when providing software updates to the mobile devices via over-the-air (OTA) connections, that the mobile device is completely recoverable in the event of failures during the update process.